2. People of the Holocene
Modern humans-in the sense of people anatomically indistinguishable from us-date back a good 130,000 years, and perhaps considerably longer. However, as a segment of the human past that is accessible through written sources history dates back no more than five thousand years. But to start history five thousand years ago is to begin in the middle of a story of rapid cultural change that actually began five thousand years earlier, with the emergence of farming. In this sense the last ten thousand years form a well-defined segment of the human past that stands in marked contrast to the much longer period preceding it.  During this period, hunting and gathering were the only way of life practiced by humans. If we call these last ten thousand years of the human past "history", we may well ask, Why did history happen when it did? Why has it all been packed into the last ten thousand years?
The first point is that the last 10,000 years-the period geologists call the Holocene-has been quite unusually warm. To find a comparable time in the preceeding period, the late Pleistocene we would have to go back to the Eemian period some 120,000 years ago. This in fact is fairly typical of the pattern of the last million years: relatively short warm periods recur every hundred thousand years or so. The second point is that the Holocene was characterised by an extraordinary climatic stability. The Eemian appears to be made up of a series of climatic peaks and valleys that were respectively far hotter and far colder than anything we have experienced in the Holocene.  The Holocene is thus a very unusual period. There has been nothing like it in the last 100,000 years, which is most of the period during which modern humans are likely to have existed.
History therefore fits snugly into the warm and stable climatic niche of the Holocene. This association hardly seems mysterious because human history is founded on farming and its development and maintenance would have been very difficult in a world climate that was cold and unstable and stable; certainly no trace of farming has yet been found in the Pleistocene.
The Holocene, then, was the window of opportunity for the making of history, and there is something about the general character of modern humans that can help explain their response to the Holocene.